In the related art, an air intake device including an air intake valve and an actuator which rotates and drives the air intake valve is known (for example, see JP-2008-38758A (Reference 1)).
The Reference 1 discloses a variable air intake device (air intake device) of a V-type internal combustion engine which is provided for each air intake pipe connecting a surge tank and each air intake port of the V-type internal combustion engine with each other and includes a variable air intake valve (air intake valve) which makes an air intake pipe length variable. In the variable air intake device of the V-type internal combustion engine, a rotation shaft of the variable air intake valve attached to an air intake pipe group corresponding to a cylinder row in one side thereof and a rotation shaft of the variable air intake valve attached to an air intake pipe group corresponding to a cylinder row in the other side extend to be parallel to each other and are rotatably attached to a valve housing. In addition, the rotation shaft in one side thereof and the rotation shaft in the other side thereof are connected to be linkable via a plurality of link members. All the variable air intake valves are configured to be synchronized and rotated with each other by the rotation shaft in the other side thereof (driven side rotation shaft) being rotated via the plurality of link members according to rotation of the rotation shaft in one side thereof (drive side rotation shaft) by driving force of the actuator. A spring is fitted to the rotation shaft in the other side thereof (driven side rotation shaft), one side end of the spring is fixed to the valve housing of an internal combustion engine main body, and the other side end thereof is fixed to the rotation shaft. Accordingly, by utilizing biasing force of the spring, rattling of a connecting portion interposed between the drive side rotation shaft, the plurality of link members and the driven side rotation shaft is configured to be suppressed.
However, in a variable air intake device of a V-type internal combustion engine described in the Reference 1, since one side end of a spring is fixed to a valve housing of an internal combustion engine main body and the other side end thereof is fixed to a rotation shaft (driven side rotation shaft) in order to suppress rattling of a connection portion between the rotation shaft and a plurality of link members, biasing force of the spring is always applied in a direction in which the driven side rotation shaft is rotated. Therefore, there is a problem that when the variable air intake valve is rotated, it is necessary to generate a torque (driving force) to overcome the biasing force of the spring in an actuator to cause the actuator to rotate the drive side rotation shaft, and thus the actuator becomes large in size.
Thus, a need exists for an air intake device which is not susceptible to the drawback mentioned above.